Not Applicable.
Not Applicable
The invention relates to an energy guiding chain for guiding for guiding cables, hoses a the like from a fixed to a movable connection point on a curved path, with chain straps which are connected to one another in articulated fashion and can be angled relative to one another, where the joint axes of at least some chain intersect.
An energy guiding chain of this type is known from EP 0 277 389, for example. This chain is formed by chain links connected to one another in articulated fashion in the known manner, where each of the chain links is formed by two chain straps arranged roughly parallel to one another, which are connected to one another by way of a lower base plate integrally molded as one piece and an upper detachable or removable cross-member. Each chain link is connected to the adjacent chain link by way of two tab-like strap projections, which snap into corresponding slit-shaped holes in the adjacent chain scraps and are connected to them in articulated fashion via pins running through the holes and the strap projections. In order to ensure the back-and-forth rolling motion of the energy guiding chain on a curvedxe2x80x94for example helicalxe2x80x94path, and in order to produce a curve in the chain, the inner straps of the chain facing the center point of the curve are shorter than the outer straps of the chain. In addition, the base plate connecting the chain straps is of trapezoidal shape. The joint axes of each chain link are at angle to one another, where the point of intersection of the axes defines the centre point of the chain curve.
Thus, the known chain can follow the path of a curve in its back-and-forth rolling motion, even if the path is inclined. This offers the advantage that, for example, rotating energy consumers, such as assembly robots and the like, can be connected by way of this kind of energy guiding chain to energy supply lines installed in a protected and strain-relieved manner.
However, the energy guiding chain disclosed in EP 0 277 389 has the disadvantage that, due to the different lengths of the straps and due to the angled position of the joint axes relative to one another, the fit between the joint connections must be very loose in order to guarantee smooth running, i.e. smooth back-and-forth rolling motion, of the chain. The known chain must be manufactured with very large tolerances. The pins and bore holes must engage with a great deal of play, because the chain must move not only in a circle, but also vertically at the same time. Due to this bending in two planes, the chain strand must be able to twist to a certain degree. In turn, the great amount of play in the joint connections makes specially designed guide elements and guide channels indispensable for lateral stabilisation of the chain. The known energy guiding chain also has the disadvantage that chain links of various shapes and sizes must be available in order to produce different radii of curvature and various interior spaces for the energy lines.
The invention is thus based on the task of improving an energy guiding chain of the type described above in such a way that it can be manufactured with joint connections of tight tolerance, while retaining good sliding and rolling properties. In particular, the chain according to the invention should be easy to assemble and ensure optimum adaptation to the movement cycle of the machine to be equipped and to the desired interior space using simple means.
The task is solved by an energy guiding chain which is characterized by the fact that the chain is formed by only one strap strand and that at least some of the chain straps are provided with at leas one support frame for accommodating the cables, hoses and the like.
A chain of this kind formed by only one strap strand has various advantages over the known chain. It is considerably easier to assemble, the joint connections can be designed with virtually no play and, above all, the width of the usable space available for accommodating cables, hoses and the like can be varied. This is especially possible through the use of the support frames provided on the chain straps for accommodating the cables.
Experiments with the energy guiding chain according to EP 0 277 389 showed that virtually the entire load of the chain strand is borne by the outer strap strand. The invention takes advantage of this by completely dispensing with one chain strand, so that, in addition to a substantial reduction in weight, the fits of the single-strand chain can be designed to be very tight, this simultaneously improving the lateral stability of the chain, as well as its flexibility and twistability. The support frames can be mounted on the inside and also the outside of the curve in the chain.
In a preferred version of the invention, the support frame is formed by upper and lower cross-members which can be attached to the chain straps in a detachable manner and which are assembled to form a closed frame by way of a detachable connecting member. Cross-members of standard, i.e. conventional, chain links can be used for this purpose.
The support frame can alternatively consist of a u-shaped bracket or the like designed as a single piece, which can be mounted on the chain straps in a detachable manner. The width and usable space of the chain can be varied by using support frames or support brackets which can be counted on the chain straps in a detachable manner.
In a particularly preferred practical example, chain straps with parallel joint axes and chain straps with intersecting joint axes are alternately connected to one another to form a chain strand, In this context, the intersecting joint axes do not all intersect at one point, but rather run along an arc. The centre point of this arc defines the centre point of the circular motion. The alternating arrangement of chain straps with intersecting joint axes and parallel joint axes has the advantage that only one chain link need be replaced at any one time in order to change the diameter of the circle.
The joint sections of chain straps with intersecting point axes are expediently formed by strap sections angled towards one another.
For example, adjacent chain straps connected to one another can overlap and display a positive fit by way of holes and pins.
It has proven to be particularly expedient for the same side of a chain strap to be positioned on top of the two directly adjacent chain straps, where one chain strap is provided with holes and the directly adjacent chain strap with protruding pains which snap into the holes of the adjacent chain strap.
In order to be able to hold the chain strand together in a secure fashion, the ends of the upper and lower cross-members on one outer strap, or the ends of the legs of the U-shaped bracket, which respectively form the support frame, are dimensioned such that they cover the overlap area with the adjacent chain straps and act as a stop to prevent separation of the chain straps transverse to the direction of motion. This type of cross-member design is known but proves to be particularly expedient for the energy guiding chain according to the invention. Each of the chain straps is expediently provided with projections designed as snap ridges, which interact in a known manner with corresponding recesses in the upper and lower cross-members or in the legs of the bracket.
As additional protection against separation of the chain straps transverse to the direction of motion, the straps provided with pins each have a shoulder around a partial length of their outer edges, which is engaged by locking projections of the straps provided with holes.
In a particularly preferred configuration of the invention, the connecting member is provided with projections designed as snap ridges, which interact with recesses in the upper and lower cross-members. In this way, the support frame for accommodating the cables can be assembled using cross-members for conventional energy guiding chains.
Instead of a support frame, at least some of the chain straps can be provided with support loops for accommodating the cables. This would further reduce the weight and dimensions of the chain according to the invention, which has a positive effect on the running properties of the chain.
To provide additional guidance, at least some of the chain straps can be equipped with guide projections on at least one of their narrow sides, which interact with a groove provided in a guide rail or the like. Guide projections of this kind, which engage the guide groove provided for this purpose with play, can be particularly expedient in the case of large chain radii. The guide projections and the guide groove prevent excessive loading of the chain transverse or tangential to its direction of motion.